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Take a simple model: the two lungs hold 300 million alveoli, and each one is a tiny ball 0.25 mm…
Contributed by StemPy LabTry it on paper first. A hint, the key idea and the worked solution are here when you need them.
Take a simple model: the two lungs hold million alveoli, and each one is a tiny ball mm across. (a) Find the surface of one alveolus in mm². (b) Find the total surface of all of them in m² (1 m² is mm²). (c) A badminton court has an area of m². What fraction of a court does your answer cover?
Need a reminder? The key ideaShow
Air passes through the nostrils, pharynx, larynx, trachea (held open by rings of cartilage), bronchi and bronchioles to the alveoli, where gases are exchanged with the blood. Breathing in, the ribs lift and the diaphragm flattens. Residual air stays in the lungs. Haemoglobin carries oxygen; most carbon dioxide travels dissolved in the plasma.
The worked solution
Have you tried it?
Work it out on paper first. It is fine to get stuck or make a mistake: that is how we learn. When you are ready, go through the solution one step at a time, and check each step against your own.
Step 1. One alveolus. mm, so mm².
Step 2. All of them. mm², which is m².
Step 3. The court. of a badminton court.
Answer: (a) mm². (b) m². (c) about of a court. Real lungs, with uneven shapes, have even more surface, about m².
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